The present invention relates to a safety device for a motor vehicle, and more specifically to a motor vehicle safety device incorporating an inflatable curtain.
When a motor vehicle is involved in an accident there is a risk that the driver and passengers within the vehicle will be injured. It has been proposed to provide vehicles with safety devices to reduce the risk of such injury.
Certain safety devices are intended to provide protection in the case of a side impact. European Patent EP-A-0808257 discloses such a device, in which an inflatable element is provided which is initially stored in position in a recess in a door frame of the vehicle. There is provided a gas generator which is adapted to generate gas, such as cold gas, the gas generator incorporating a sensor which senses a side impact and/or roll-over situation and subsequently activates the gas generator at an appropriate instant. The gas generator is connected to the inflatable element, and when a side impact occurs, the gas generator generates cold gas which inflates the inflatable element. The inflatable element thus moves from its initial stored position within the recess in the door frame, to the operative position, where it forms a substantially flat curtain located between the head of the person and the adjacent window.
A problem associated with such side impact safety devices is that of providing a tensioning means for the inflatable element when it is in an operable position, so that it offers sufficient protection against the head of a person passing through the window. In the case of EP-A-0808257, where the recess in which the inflatable element is initially stored spans at least one of the “A” and “C” posts of the vehicle such that it is non-linear, the inflatable element is separated into a plurality of vertical cells. Upon inflation, the lower edge of the inflatable element is thus decreased in length which, as a result of the upper edge of the inflatable element being fixedly attached to the non-linear door frame, creates a tension in the lower edge of the inflatable element, holding the inflatable element in place and offering protection for the passenger in a roll-over situation.
U.S. Pat. No. 6,241,277 discloses an arrangement for tensioning a side airbag when the recess in the door frame in which the airbag is initially stored is substantially linear. Two pulleys are provided, one fixed to the door frame of the motor vehicle, above the recess in which the airbag is initially stored, and the other fixed to a point on the motor vehicle in a position in front of the leading edge of the airbag. A cord is attached, at one end, to the leading edge of the airbag and, at the other end, to a point on the airbag positioned rearwardly of the leading edge. The cord is substantially inextensible except for an elastic portion which is initially under little or no tension. During a side impact situation, the airbag is inflated downward toward the base of the window of the motor vehicle and the cord and pulley system are positioned such that, as the airbag moves downwardly, tension is created in the elastic portion of the cord, the tension having a component along the lower edge of the airbag as desired.
It is an object of the present invention to provide an improved safety device incorporating a tensioning system for tensioning an inflatable curtain.